Test 4: lecture 4: male Flashcards
function of testis
endocrine → testosterone
exocrine → sperm
Synthesize and secrete testosterone in response to LH
leydig cells (interstitial cells)
outside the seminiferous tubule
similar to theca cells in female
sertoli cells
sustentacular cell (nurse cells)
blood-testis barrier
• Convert testosterone to DHT and estrogen in response to FSH
• Secrete androgen-binding protein, inhibin, AMH
___ connect sertoli cells and prevent things from passing into the lumen of the seminiferous tubule
tight junction
three regions of the epididymis
caput (head)
corpus (body)
cauda (tail)
roles of the epididymis
absorb fluid (principle cells)
movement
maturating of sperm
storage of sperm
how does sperm maturation work in the epididymis
Plasma membrane undergoes changes
- Cytoplasmic droplet is removed (fall off the tail of the sperm)
- Sperm start swimming
- Maturation is completed inside the female
functions of the accessory sex glands
seminal plasma → nutrient sperm, protect sperm, lubrication
prostaglandins cause smooth muscle contraction → will cause uterus to contract and move sperm into uterine tubes
seminal plasma
Lubricate during copulation
- Neutralize acidic female tract
- Nourish and protect viable sperm, help target nonviable sperm for destruction
- Maintain membrane stabilization/delay capacitation
- Promote sperm transport in female tract
- Induce ovulation in some species → camalids (llama)
- Mediate sperm binding to uterine tube epithelial cells
- Contribute to copulatory plug
The amount of SP and semen concentration that enters the uterus
varies
columns of the penis
corpus spongiosum → glands penis (area around the urethra
corpus cavernosum→ fill with blood → rigidity
round spermatids morph into elongated spermatids
Spermiogenesis:
creates haploid spermatocytes
meiosis
the mitotic phase of spermatogenesis; produces spermatocytes from spermatogonia (diploid)
Spermatocytogenesis
spermatogenesis
the production of spermatozoa
• Spermatocytogenesis: the mitotic phase of spermatogenesis;
produces spermatocytes from spermatogonia (diploid)
• Meiosis: creates haploid spermatocytes
• Spermiogenesis: round spermatids morph into elongated spermatids
undifferentiated male germ cell
Spermatogonium(a)
• Males are born with a finite number of spermatogonia
produced by mitosis of spermatogonia and will undergo meiosis
Spermatocyte
the haploid result of meiosis
spermatids
Round: still have lots of cytoplasm and organelles
Elongated: have shed much of cytoplasm and organelles; have a tail.
The release of elongated spermatids from the Sertoli cell into the lumen of the seminiferous tubule
spermiation
the haploid product of spermatogenesis.
spermatozoa
spermatogonia→ spermatocytes→ haploid spermatocytes → spermatids → spermatozoa
Spermatogonia produce an infinite number of spermatozoa
spermatogenesis
mitosis (connects to each other by bridge)
meiosis
compare mitosis vs meiosis in male and female
retinoic acid is important for
differentiation of spermatogonia(4N) to spermatocytes (2N)
(mitosis → type A→ type B cells)
mitosis → meiosis
how does sperm move in seminiferous tubule
contraction of the tubule
spermatids have tails but they have not learned to swim yet
___ cells convert testosterone to DHT
Sertoli
___ enhances concentrations of androgens in the testes
Androgen binding protein (ABP)
___ triggers production of testosterone in Leydig cells
LH
LH enhances production of StAR which will
help move cholesterol into mitochondria
___ Promotes spermatogeneis, spermatocyte maturation, and spermiation; synthesis of ABP, inhibin, activin, estrogen
FSH
negative feedback of spermatogenesis
hormone in spermatogenesis
LH binds to leydig cells and cause the release of testosterone
testosterone moves across the basement membrane into the sertoli cell
FSH binds to sertoli cell and causes the release of ABP and aromatase, the ABP and testosterone move into the lumen of the seminiferous tubule
aromatase converts testosterone → estrogen (estradiol)
estrogen will travel back into leydig cell and increase testosterone release
why are abusers of anabolic steroids frequently infertile?
negative feedback
anabolic steroid reduce FSH and LH which leads to decrease of testosterone in the seminiferous tubules
what happens to DNA in sperm
moves from histones to protamine
allows for super coiling → inactivates
pathway of ejaculation
Seminiferous tubules
Rete testis
Efferent ductules
Epididymis
Vas deferens
phases of sexual response for males
Erection: parasympathetic response
Emission: sympathetic response
Ejaculation: sympathetic response
Upon ovulation, sperm are released and undergo ___prior to fertilization
hyperactivation and capacitation
increase Calcium into the sperm (fast swimming)
increased fluidity → plasma membrane changes
what causes the breakdown of the zona pellucida
binding of sperm
acrosome reaction
binding of sperm causes
acrosome reaction
breakdown of the zona pellucida and release of cortical granules into the perivitelline space
this causes ZP to harden and prevent polyspermy
meoisis II is resumed and completed
granules from the sperm are released into the ___ during the acrosome reaction
perivitelline space
(slow block → calcium release causes hardening of the ZP that prevents other sperm from entering)
fertilization causes the formation of ___ that fuse to form the zygote
pronucleus
prepuberty
Hypothalamic pituitary gonadal axis is suppressed, and GnRH secretion is maintained at low levels
gonadostat hypothesis
during prepuberty sex organs work but they are very sensitive to negative feedback → kept turned off. At puberty something changes and they are less sensitive and now work
Puberty
Hypothalamus becomes less sensitive to negative feedback, and a new set point is created
• GnRH increases
- FSH and LH increase
- Steroid hormone levels rise
Secondary sex characteristics develop
steps of meiosis
